How to run multiple futures concurrently?

June 17, 2024

I’m running a http server using actix_web which has an endpoint that receives some files, which I need to process. For the async runtime, I’m using tokio. The thing is, I want to process the files concurrently, but there are some issues.

The first issue is that the body doesn’t live long enough, since it’s not ' static typed.
The second issue is that I need to pass some variables to the function that actually process the file, but I’m getting the use of moved value error.

This is the code:

#[post("/images")]
async fn process_images(
    body: Json<ProcessFilesBody>,
    aws: Data<AWSService>,
) -> Result<impl Responder, Error> {
    println!("PROCESSING {:?} FILES", body.0.files.len());

    let mut futures = Vec::new();

    for file in &body.0.files {
        let handle = spawn(async move {
            process_file(aws.clone(), &file).await;
        });
        futures.push(handle);
    }

    for handle in futures {
        handle.await.unwrap();
    }

    Ok(HttpResponse::Ok())
}

I’ve tried wraping the aws variable in an Arc but didn’t work and I have no clue how to fix the lifetime of the files

>Solution :

Clone body.0.files outside the loop to resolve the lifetime issue.

Use aws.get_ref().clone() to clone the inner AWSService.

#[post("/images")]
async fn process_images(
    body: Json<ProcessFilesBody>,
    aws: Data<AWSService>,
) -> Result<impl Responder, Error> {
    println!("PROCESSING {:?} FILES", body.0.files.len());

    let files = body.into_inner().files.clone(); // Clone files here
    let aws_service = aws.get_ref().clone(); // Clone AWSService here
    let mut futures = Vec::new();

    for file in files {
        let aws_clone = aws_service.clone(); // Clone for each async block
        let handle = tokio::spawn(async move {
            process_file(aws_clone, file).await;
        });
        futures.push(handle);
    }

    for handle in futures {
        handle.await.unwrap();
    }

    Ok(HttpResponse::Ok())
}